1. How compatible are the documents created by Pages and Keynote with their Word and PowerPoint counterparts in Office 2003 (Windows) and Office 2004 (Mac)?

2. For an existing user of Office 2004, are there good reasons to buy a copy of iWork 06 or would you consider it unnecessary? I'm all for making my life easier and adding a bit more interest to my documents so I'd entertain the idea of using both suites if it is worth it.